You've installed new LED panels. They give plenty of light, but after an hour at your screen your eyes are burning and your head starts to throb. In that case the problem often isn't too little light, but glare. And that's exactly what the UGR value is about. Now that it gets dark earlier in the evening and you work under artificial light more often, it's especially worth understanding. In this guide I explain what UGR is, which value you need per room, what the difference is between UGR<19 and UGR<22 and what to look out for when buying LED lighting.
In short
- UGR: stands for Unified Glare Rating. It indicates how much glare a lighting installation causes in a room. The lower the number, the less discomfort.
- Office and screen work: choose UGR<19. For drawing work the guideline value is even lower, UGR<16.
- Entrance and general areas: UGR<22 is fine there. For storage, stairs and archives the guideline value is UGR<25, for corridors UGR<28.
- Not the same as lumens: a light with lots of lumens can be pleasant or dazzling. The shielding and the placement make the difference.
- When buying, check: the UGR value, the diffuser and whether the panel is flicker-free.
Jump straight to:
What is UGR?
UGR stands for Unified Glare Rating. It's a number that indicates how much discomfort glare a lighting installation causes in a room. Glare occurs when your eyes are bothered by overly bright light sources in your field of vision, or by reflections on your screen or worktop. You see less sharply, you squint and after a while you get tired.
The lower, the better
A low UGR means little glare. A value below 15 gives the least glare, and in practice most values lie between 15 and 30. A fixture with UGR<19 therefore causes clearly less glare than a fixture with UGR<25.
What does the < sign (less than) mean?
With LED panels you often see UGR<19 or UGR<22. This means the calculated value stays below that number. A panel with UGR<19 therefore meets the requirement for offices, a panel with UGR<22 the requirement for an entrance, for example.
An indication, not a guarantee for your room
The UGR a manufacturer states is calculated for a standard situation. In your room the actual value may turn out slightly different, due to the dimensions, the ceiling height, the colour of the walls and where you sit. So use the value as a reliable comparison between lights, and place them smartly (see the tips further down).
Which UGR do you need? The guideline values
The guideline values are set out in the standard NEN-EN 12464-1, the European standard for the lighting of indoor workplaces. Here's what that looks like for common rooms:
| Room | Guideline value |
|---|---|
| Drawing office, technical drawing | UGR<16 |
| Office, screen work | UGR<19 |
| Entrance and reception | UGR<22 |
| Storage, archives, stairs and lifts | UGR<25 |
| Corridors and circulation areas | UGR<28 |
| Workshop and production | Depends on the work: the finer the work, the lower the value |
What determines the UGR of a light?
UGR is not a property of the light source alone. It's about the entire fixture and the room. These are the factors that matter most:
The diffuser
A good diffuser spreads the light over a larger surface, so there are no harsh bright spots. Panels with a prismatic or opal diffuser therefore cause much less glare than a bare LED chip or an open spotlight.
The brightness of the surface
It's not just the number of lumens that counts, but also how much light comes from one small area. Lots of lumens from a small surface is harsh and uncomfortable, the same lumens from a large panel is calmer. You can read what lumen means in What is lumen?.
Installation and viewing angle
A panel that sits flush in the ceiling is less visible from an oblique angle than a pendant fixture. Glare also depends on how you look at the light: directly under a light you don't see it, from the other side of the room you do.
The room itself
Light, matt walls and a light ceiling distribute the light better. Glossy floors, glass walls and shiny desks reflect the light straight back into your eyes.
How to choose the right LED lighting in five steps
1. Determine what you do in the room
If you work at a screen for hours, you want UGR<19. If it's an entrance, hallway or warehouse, a higher value is acceptable.
2. Choose the matching UGR
Use the table above. If you want an extra margin, choose a lower value than required. A panel with UGR<19 can be used anywhere UGR<22 is sufficient, but not the other way round.
3. Determine how much light you need
For office work, around 500 lux on the work surface is usually the target. How many panels you need for that depends on the floor area and the lumens per panel. You'll find a worked example in What is lumen? Lumens, watts and lux explained simply.
4. Choose the light colour
For offices, cool white 4000K is the familiar choice: bright and neutral. 5000K and 6000K are sharper and suit workshops and technical rooms. See LED colour temperature.
5. Check for flicker-free operation and colour rendering
A light that doesn't dazzle but does flicker is still tiring. Choose a flicker-free panel with good colour rendering (CRI 80 or higher). You can read more about flickering in Solving LED lighting problems.
Which UGR per room? My choice
Office and screen work: UGR<19
For an office, practice room or meeting room, choose a panel with UGR<19. I have them in the 60x60 cm size in cool white 5000K and daylight white 6000K, 5000 lumens (25W/18W), in a box of 8 pieces for € 339,95. That's about € 42,50 per panel. If your ceiling has slightly larger grid tiles, there's also the 62x62 cm version (€ 364,95 per box of 8).
Long narrow rooms: the 30x120 cm panel
If it suits your ceiling or corridor better, choose the LED panel 30x120 cm, UGR<19, cool white 4000K (€ 364,95 per box of 8). This is the colour temperature most often chosen for offices. Also available in 5000K and 6000K.
Entrance, shop and general areas: UGR<22
Where nobody sits at a screen for hours, UGR<22 is sufficient and saves on the price. For example the LED panel 60x60 cm, 36W, 3960 lumens, cool white 4000K (€ 159,95 per box of 8, so about € 20 per panel) or the energy-efficient 28W version with 4200 lumens (€ 179,95 per box of 8).
Workshop, warehouse and industrial hall
Here the lights hang higher and the requirement is often less strict, but fine work calls for calm light. Have a look at the LED high bays and read LED workshop lighting: how much lux and which lights? and Professional LED lighting for industrial halls, warehouses, offices and outdoor sites.
Home office
If you work at a screen a lot at home, the same principles apply as in the office: choose UGR<19 and place the light smartly. See Desk lighting for working from home and the collection LED office lighting. If you only need one or two panels, just send me a message and I'll help you think it through.
Placement: how to avoid glare
Even with a low UGR, a bad position can still cause discomfort. These rules help:
Don't hang the light directly above or behind your screen
The light will then reflect in your monitor. Place panels beside and above your workstation instead, in rows running parallel to your line of sight.
Position your screen at right angles to the window
Daylight and artificial light at the same time quickly cause reflections. A screen placed at right angles to the window suffers least from this.
Choose matt surfaces
A matt desktop and matt walls keep the light soft. Gloss creates bright spots.
Spread the light over more fixtures
Several panels with moderate light are better than one very bright point. That way the lighting is even and there are no dark corners.
Common mistakes
Buying on lumens alone
A panel with lots of lumens and a poor diffuser is harsh, not pleasant. Also look at the UGR value.
UGR<22 in an office with screen work
UGR<22 is fine for an entrance, not for an office. Choose UGR<19 there.
Open spotlights and bare bulbs at eye level
Unshielded spotlights are the best-known cause of glare. You can read how to position spotlights properly in Positioning LED spotlights.
Replacing an old fluorescent fixture without looking at the shielding
LED tubes in an old fixture without proper shielding quickly cause glare. An LED panel is often the better replacement. See Replacing fluorescent tubes with LED.
📩 More LED tips in your inbox?
Sign up and you'll immediately get 5% welcome discount in your inbox. After that I'll send you a new LED tip every now and then. You can unsubscribe at any time.
Frequently asked questions
What does UGR mean?
What is the difference between UGR<19 and UGR<22?
Which UGR do I need for a home office?
Is a lower UGR always better?
Does UGR have anything to do with lumens?
Where can I find the UGR value of a light?
Is UGR a legal requirement?
Which light colour goes with a low UGR?
Regards,
Bas / LEDPLANET.NL